[MB1968]

@latts9923 and @Juan Mortyme

Thank for the input. I did a test on a fresh Leia install with only one Artist (Queen). In the extrafanart folder I've put fanart1,fanart2 etc images andI noticed the following.
In the Shelf3D view I can see the 6 fanarts rotating from the extrafanart folder in the right upper corner of the screen, However, in the background, the skin is ignoring the extrafanart folder and shows many more fanart images. Probably downloaded rom fanart.tv.

I've disabled online sources in the meta module. To be honest, I'm always unsure whether I have to enable or disable this setting. Do all layouts for music work fine (banners, studio logos) work fine, when disabling online sources?

@MB1968 

Yes, the art you have saved locally should all work. The only downside to disabling online art, that I can tell, is if you use Kodi for radio. In that case only local art is used so if the song playing is by an artist you don't have in your Artist Information folder you won't see any art at all. Other than that it should be fine. Also check you settings for the Artist Slideshow add-on as it too can fetch online art if left in it's default settings. One other thing, something is definitely pulling info from somewhere because it is populating the artist's discography in the Info View, but I have no idea what add-on is getting it or from where?

I  took a closer look and the Shelf3D view is cycling the art in both the background and the thumbnail window. I checked a few different views for music and they all seem to working fine (@latts9923  at least on Leia version, the Matrix version on the other hand, extrafanart for artist's is not working at all) so I can verify for you that my extrafanart is working, provided it's in a subfolder. I've also noticed that it seems like a "fanart0.jpg" needs to be in the extrafanart folder. As well, I don't think it makes a difference but I have my artist extrafanart duplicated with copies in both the artist main folder and extrafanart subfolder. I'm a little hesitant about removing the artists' extrafanart subfolders until I'm absolutely convinced they aren't needed but nonetheless I'm preparing for that eventuality. Now, I'm assuming you are talking about albums and singles when referring to 'music'? I only ask because all bets are off if you are browsing music videos by artist. The artist art while browsing music videos is a complete and utter cluster f**k.

We're talking about the music library

I'm glad for you everything is working as it should on your system, although you need to duplicate the fanart0, fanart1 etc images in an extrafanart folders. I did so for my tv shows.

I did a test. I've put an image from an different artist in the extrafanart folder. In the Shelf3D view I can see this image immediately in the thumbnail window. However, in the background it never appears. I ran AWB add missing artwork.

I now have 7 different fanart images in the extrafanart folder. In the background I'm seeing images, that I have never stored in the extrafanart folder. I'm pretty sure my local images are being ignored. I noticed this behaviour, because for a lot of artist in my library there's no online fanart available. This used to work fine previously. I only see the default fanart for these less known artists now.

EDIT: I'm experiencing the same issue under Matrix. A lot of live concert images for Queen in the background. I did not download these images to my Artist Information folder.